Abstract:The world of crystallography was forced to reassess its rules about thirty years ago with the introduction of the concept of quasicrystals, solids with rotational symmetries forbidden to crystals, by Levine and Steinhardt (1984) and the discovery of the first examples in the laboratory by Shechtman et al. (1984). Since then, >100 different types of quasicrystals have been synthesized in the laboratory under carefully controlled conditions. The original theory suggested that quasicrystals can be as robust and s… Show more
“…It belongs to the Al-Cu-Fe system and exhibits the composition Al 62.0(8) Cu 31.2(8) Fe 6.8(4) , which is outside the measured equilibrium stability field at standard pressure of the previously reported Al-Cu-Fe quasicrystal121314 (Al x Cu y Fe z , with x between 61 and 64, y between 24 and 26, z between 12 and 13%). The new icosahedral phase was found in one of the meteoritic fragments of the same Khatyrka meteorite recovered from an expedition to the Koryak Mountains in far eastern Russia in 201157 as a result of a search for material that would provide information on the origin of icosahedrite, the first natural quasicrystal. The fragment is labeled Grain 126A to distinguish it from others of Grain 126.…”
mentioning
confidence: 94%
“…The first quasicrystalline phase found in nature, icosahedrite Al 63 Cu 24 Fe 13 34, displayed a five-fold symmetry in two dimensions and icosahedral symmetry in three dimensions and was found in the Khatyrka meteorite, a CV3 carbonaceous chondrite567. The discovery represented a breakthrough in mineralogy and in condensed matter physics.…”
We report the first occurrence of an icosahedral quasicrystal with composition Al62.0(8)Cu31.2(8)Fe6.8(4), outside the measured equilibrium stability field at standard pressure of the previously reported Al-Cu-Fe quasicrystal (AlxCuyFez, with x between 61 and 64, y between 24 and 26, z between 12 and 13%). The new icosahedral mineral formed naturally and was discovered in the Khatyrka meteorite, a recently described CV3 carbonaceous chondrite that experienced shock metamorphism, local melting (with conditions exceeding 5 GPa and 1,200 °C in some locations), and rapid cooling, all of which likely resulted from impact-induced shock in space. This is the first example of a quasicrystal composition discovered in nature prior to being synthesized in the laboratory. The new composition was found in a grain that has a separate metal assemblage containing icosahedrite (Al63Cu24Fe13), currently the only other known naturally occurring mineral with icosahedral symmetry (though the latter composition had already been observed in the laboratory prior to its discovery in nature). The chemistry of both the icosahedral phases was characterized by electron microprobe, and the rotational symmetry was confirmed by means of electron backscatter diffraction.
“…It belongs to the Al-Cu-Fe system and exhibits the composition Al 62.0(8) Cu 31.2(8) Fe 6.8(4) , which is outside the measured equilibrium stability field at standard pressure of the previously reported Al-Cu-Fe quasicrystal121314 (Al x Cu y Fe z , with x between 61 and 64, y between 24 and 26, z between 12 and 13%). The new icosahedral phase was found in one of the meteoritic fragments of the same Khatyrka meteorite recovered from an expedition to the Koryak Mountains in far eastern Russia in 201157 as a result of a search for material that would provide information on the origin of icosahedrite, the first natural quasicrystal. The fragment is labeled Grain 126A to distinguish it from others of Grain 126.…”
mentioning
confidence: 94%
“…The first quasicrystalline phase found in nature, icosahedrite Al 63 Cu 24 Fe 13 34, displayed a five-fold symmetry in two dimensions and icosahedral symmetry in three dimensions and was found in the Khatyrka meteorite, a CV3 carbonaceous chondrite567. The discovery represented a breakthrough in mineralogy and in condensed matter physics.…”
We report the first occurrence of an icosahedral quasicrystal with composition Al62.0(8)Cu31.2(8)Fe6.8(4), outside the measured equilibrium stability field at standard pressure of the previously reported Al-Cu-Fe quasicrystal (AlxCuyFez, with x between 61 and 64, y between 24 and 26, z between 12 and 13%). The new icosahedral mineral formed naturally and was discovered in the Khatyrka meteorite, a recently described CV3 carbonaceous chondrite that experienced shock metamorphism, local melting (with conditions exceeding 5 GPa and 1,200 °C in some locations), and rapid cooling, all of which likely resulted from impact-induced shock in space. This is the first example of a quasicrystal composition discovered in nature prior to being synthesized in the laboratory. The new composition was found in a grain that has a separate metal assemblage containing icosahedrite (Al63Cu24Fe13), currently the only other known naturally occurring mineral with icosahedral symmetry (though the latter composition had already been observed in the laboratory prior to its discovery in nature). The chemistry of both the icosahedral phases was characterized by electron microprobe, and the rotational symmetry was confirmed by means of electron backscatter diffraction.
“…The rock sample was subsequently shown to be a fragment of the Khatyrka meteorite, an oxidized subgroup (Allende-like) CV3 carbonaceous chondrite (CV3 CC), which formed at least 4.5 billion years ago 5 . Additional samples of the Khatyrka meteorite were recovered in an expedition to the Koryak Mountains in Chukotka in 2011 6 7 . A study of those samples provided clear evidence that the meteorite was subjected to a high-pressure shock and that the shock produced a heterogeneous distribution of high pressure and temperature followed by rapid cooling 8 .…”
We report the first occurrence of a natural quasicrystal with decagonal symmetry. The quasicrystal, with composition Al71Ni24Fe5, was discovered in the Khatyrka meteorite, a recently described CV3 carbonaceous chondrite. Icosahedrite, Al63Cu24Fe13, the first natural quasicrystal to be identified, was found in the same meteorite. The new quasicrystal was found associated with steinhardtite (Al38Ni32Fe30), Fe-poor steinhardtite (Al50Ni40Fe10), Al-bearing trevorite (NiFe2O4) and Al-bearing taenite (FeNi). Laboratory studies of decagonal Al71Ni24Fe5 have shown that it is stable over a narrow range of temperatures, 1120 K to 1200 K at standard pressure, providing support for our earlier conclusion that the Khatyrka meteorite reached heterogeneous high temperatures [1100 < T(K) ≤ 1500] and then rapidly cooled after being heated during an impact-induced shock that occurred in outer space 4.5 Gya. The occurrences of metallic Al alloyed with Cu, Ni, and Fe raises new questions regarding conditions that can be achieved in the early solar nebula.
“…1), as typically observed for other fragments of the Khatyrka meteorite 4,7,13,14 . Detailed examination by scanning electron microscopy, single-crystal X-ray diffraction, micro-computed tomography and transmission electron microscopy of fragments from Grain 126 associated to proxidecagonite revealed the presence of trevorite, diopside, forsterite, ahrensite, clinoenstatite, nepheline, coesite, stishovite, pentlandite, Cu-bearing troilite, icosahedrite, khatyrkite, taenite, Al-bearing taenite, steinhardtite, decagonite, hollisterite, stolperite and kryachkoite 4,5,7,13,15–17 . The recovery of different Al-Ni-Fe crystalline (steinhardtite) and QC (decagonite) intermetallic phases, motivated a careful search for other metallic fragments, which led to the discovery of a particle with composition close to that of the known Al-Ni-Fe decagonal QC but with different diffraction characteristics.…”
We report the discovery of Al34Ni9Fe2, the first natural known periodic crystalline approximant to decagonite (Al71Ni24Fe5), a natural quasicrystal composed of a periodic stack of planes with quasiperiodic atomic order and ten-fold symmetry. The new mineral has been approved by the International Mineralogical Association (IMA 2018-038) and officially named proxidecagonite, which derives from its identity to periodic approximant of decagonite. Both decagonite and proxidecagonite were found in fragments from the Khatyrka meteorite. Proxidecagonite is the first natural quasicrystal approximant to be found in the Al-Ni-Fe system. Within this system, the decagonal quasicrystal phase has been reported to transform at ~940 °C to Al13(Fe,Ni)4, Al3(Fe,Ni)2 and the liquid phase, and between 800 and 850 °C to Al13(Fe,Ni)4, Al3(Fe,Ni) and Al3(Fe,Ni)2. The fact that proxidecagonite has not been observed in the laboratory before and formed in a meteorite exposed to high pressures and temperatures during impact-induced shocks suggests that it might be a thermodynamically stable compound at high pressure. The most prominent structural motifs are pseudo-pentagonal symmetry subunits, such as pentagonal bipyramids, that share edges and corners with trigonal bipyramids and which maximize shortest Ni–Al over Ni–Ni contacts.
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